Antiperspirant Active Compositions and Manufacture Thereof

Abstract

An antiperspirant active composition comprising an aluminum salt, the aluminum salt (i) having an aluminum to chloride molar ratio of 0.3:1 to 3:1; and (ii) exhibiting an 27Al NMR spectrum with a species distribution including at least 90% A130 polyhydroxyoxoaluminum cation as the predominant species detectable by 27Al NMR within the aluminum salt. The composition can optionally include zirconium. Also disclosed are a method of making an antiperspirant active composition and the use of a heating step at elevated temperature to convert Al13 polyhydroxyoxoaluminum cations in the species detectable by 27Al NMR within an aqueous aluminum salt solution into Al30 polyhydroxyoxoaluminum cations in the species detectable by 27Al NMR without increasing a SEC Peak 3 area in the SEC chromatogram of the aluminum salt.

Description

BACKGROUND[0001]The invention relates to antiperspirant active compositions comprising an aluminum salt and to methods of making an antiperspirant active composition.[0002]Antiperspirant salts, such as aluminum chlorohydrex (also called aluminum chlorohydrex polymeric salts and abbreviated here as “ACH”) and aluminum zirconium glycine salts (abbreviated here as “ZAG”, “ZAG complexes” or “AZG”), are known to contain a variety of polymeric and oligomeric species with molecular weights (MW) of 100 Da-500,000 Da. It has been clinically shown that, in general, the smaller the species, the higher the efficacy for reducing sweat.[0003]In an attempt to increase the quality and quantity of smaller aluminum and / or zirconium species, a number of efforts have focused on: (1) how to select the components of ACH and ZAG that affect the performance of these materials as antiperspirants; and (2) how to manipulate these components to obtain and / or maintain the presence of smaller types of these comp...

AI Technical Summary

Benefits of technology

[0020]The Al30 polyhydroxyoxoaluminum cation is more stable than the Al13 polyhydroxyoxoaluminum cation, and both the Al30 and Al13 polyhydroxyoxoaluminum cations elute under SEC Peak 4, and so have high antiperspirant efficacy. Accordingly, the present invention is predicated on the finding that an antiperspirant salt can be produced containing primarily Al30 in the Al species, so as to provide a highly stable antiperspirant active, and with high antiperspirant efficacy because of high Peak 4 area, but low, or negligible, or even entirely absent, Peak 3 area. The present inventors believe that no current methods exist in the art to synthesize the efficacious and stable Al30 polyhydroxyoxoaluminum cation without fainting significant amounts of large Al species which would elute under SEC Peak 3 and therefore reduce antiperspirant efficacy.

[0021]The present inventors have devised an antiperspirant active composition which has high antiperspirant efficacy and stability, and a method of manufacture thereof, and in particular synthesize the efficacious and stable Al30 polyhydroxyoxoaluminum cation without forming significant amounts of large Al species which would elute under SEC Peak 3 and therefore reduce antiperspirant efficacy.

[0048]The present invention also provides the use, for enhancing the stability of an aluminum salt of an antiperspirant active composition without increasing a SEC Peak 3 area in the SEC chromatogram of the aluminum salt, of heating, at a temperature of 50° C. to 100° C. for a period of time of at least 6 hours or , in other embodiments, at least 12 hours, an aqueous solution of the aluminum salt having an aluminum to chloride molar ratio of 0.3:1 to 3:1; a buffer, the buffer being an amino acid or betaine and a molar ratio of buffer to aluminum being at least 0.1:1; an OH:Al molar ratio of at most 2.6:1; and a pH of 2 to 5.

Problems solved by technology

Therefore the data published by Chen et al shows that prolonged heating of an Al13 solution with the aim of trying to synthesize Al30 may result in unacceptably low Al30 concentrations and, importantly for aluminum antiperspirant actives, produce NMR-inactive Al species that may elute under Peak 2 or Peak 3 and reduce antiperspirant efficacy.

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